Batteries such as alkaline storage batteries and lithium ion secondary batteries are widely used as the power source for portable devices, machine tools, or electric vehicles. Of these, nickel metal-hydride storage batteries have a relatively high energy density and excellent durability, and the applications thereof, including as power sources for electric vehicles, are being expanded.
Generally, the main components of nickel metal-hydride storage batteries include: a positive electrode formed by filling a three-dimensional metal porous material with nickel hydroxide and other materials; and a negative electrode formed by applying an electrode mixture paste composed of a hydrogen-absorption alloy and other materials to porous metal thin plate (hereinafter simply abbreviated as a “core material”) such as a punched metal. Of these two, the negative electrode can be produced continuously because of the nature of its production process, which has received attention as a highly efficient process. Specifically, a method has been proposed in which, after the core material is immersed in the electrode mixture paste, the application amount of the electrode mixture paste is adjusted to produce a paste-coated sheet.
The produced paste-coated sheet is wound in a coil shape in order to convey to the next step (such as a rolling step). In order to stabilize the operation of the next step, the winding accuracy of the paste-coated sheet must be improved. As concrete measures, a method has been proposed in which the position of an edge portion in the width direction of a travelling paste-coated sheet is detected, and is remedied when the detected position is displaced (see, for example, Patent Document 1).    [Patent Document 1] Japanese Patent Laid-Open Publication No. 2000-228188